Making perborate containing detergents



2 5 2 9 9 crass United States Patent MAKING PERBORATE CONTAINING DETERGENTS Bruce Strain, Wyoming, and Stanley L. Eaton and Kenneth R. Ericson, Cincinnati, Ohio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio hydrate is mixed with granular detergent and the mixture is brought to a temperature above 145 F., a fusion" of the perborate with detergent granules results without sigcant change in the particulate form of the detergent.

f is our theory, to which the invention is not limited,

that at such temperatures the sodium perborate tetrahydrate melts or becomes dissolved in its water of crystallization to form a solution which immediately coats or is absorbed upon the surfaces and within the pores of 10 the spray dried detergent. Promptly after such absorption of the sodium perborate tetrahydrate, the mixture is j cooled to minimize decomposition of perborate. During such cooling, the perborate solidifies, but the solidperharateflirp ed is imbedded in or entrained in the surfaces T e Pfflsent mvefltlon relates to ckanmg and Washmg and outer pores of the detergent granules and is not free No Drawing. Application April 8, 1955 Serial No. 500,282

2 Claims. (Cl. 252-97) agents having bleaching properties, and more particularly concerns the provision of a detergent-perborate washing composition which is stable against gravitational separation of perborate during handling.

As will be clear from the description which follows, 2

the invention is applicable in the preparation of soap and anionic and nonionic synthetic detergent compositions in granular form, hereinafter referred to generically as noncationic synthetic organic detergents.

Mechanical mixtures of granular detergents, especially spray dried detergents, and crystalline sodium perborate tetrahydrate have been prepared previously. However, such mechanical mixtures, due to the wide diflerence in specific gravity of the detergent and the perborate, have the disadvantage of tending to separate or segregate during handling so that the perborate is not uniformly distributed throughout the entire composition when it reaches the ultimate consumer.

Efforts have heretofore been made to reduce or eliminate such endency toward segregation of constituents, notably by the use of agents which adhesively join small crystals of perborate to particles of granular detergent. However, such efforts have been only partially successful and segregation during normal handling has been reduced only a minor degree.

Other charts to obtain a detergent-perborate composition in granular form have involved introduction of the perborate into the crutcher mix before spray drying.

Such procedures have met with little success due to the tendency of the perborate to decompose at the conventional temperatures used in spray drying operations.

It is an object of the present invention to produce an improved detergent composition having washing, cleaning and bleaching properties in aqueous solution.

A further object is to provide a gravitationally stable mixture of detergent and sodium perborate tetrahydrate in granular or particulate form.

Another object is to provide an improved process for producing a gravitationally stable detergent-perborate composition in spray dried form without substantial decomposition of perborate.

A still further object is to produce a granular detergentperborate bleaching and cleansing composition which is stable against separation of perborate particles from detergent particles.

Other objects will be apparent from the following description and specific examples.

In accordance with the present invention, the tendency toward segregation or gravitational separation of perborate is eliminated, and the objects of the invention are achieved without significant decomposition of the perborate. Thus, as far as we are aware, our process produces a novel form of granular detergent with bleaching properties in that the perborate is entrained in the porous structure of the granular detergent and is not subject to gravitational separation during handling.

We have discovered that when sodium perborate tetrato segregate during normal handling of the product.

It is known that sodium perborate tetrahydrate tends to decompose if held at temperatures above 145' F. for appreciable periods of time, the rate of decomposition increasing with temperature. In the present process, sub stantial decomposition is avoided by adjusting the time and temperature of exposure of the detergent-perborate mixture to achieve fusion and absorption with minimum decomposition. Thus, if suitable granule-cooling facilities such as an air conveyor are provided, the treated granules can be rapidly cooled to a temperature below 145 F. to eflfect resolidification of the absorbed perborate and remove all danger of decomposition. Under such conditions, exposure of the perborate to elevated temperatures can be held to less than five minutes without difiiculty and temperatures as high as 250' F. can be tolerated without a major amount of decomposition. However, we prefer to effect fusion and absorption at lower temperatures within the range of about 150 F. to about 230 F. and to operate so that the total exposure time of the perborate to the elevated temperature is not substantially more than one minute, thus avoiding significant decomposition. In conventional methods of granular detergent production, wherein granules at temperatures from 180 F. to 220 F. issue from the base of the spray drying tower and enter a rotating drum where liquid organic builder substances are customarily sprayed on the granules, the perborate can be introduced prior to entrance of the granules into the rotating drum. The temperature of the granules is sufliciently high to efiect fusion of the perborate tetrahydrate, and absorption is substantially instantaneous. The resulting product is subsequently delivered to an air lift where cooling of the granules is efiected within a period of to seconds after the perborate is added to produce the improved product of the present invention without measurable perborate decomposition.

If desired, the sodium perborate tetrahydrate crystals can be admixed with cold detergent granules, following 5 which the mixture is rapidly heated to a temperature above F., preferably from about F. to about 230 F. with agitation to gggggiusionap d absorption of the pr'libm cooling of the product may be efleci y means of an air lift or by allowing the granules to fall through a counter-current stream of cooling air.

lition with mild bleaching action is desired, the amount of sodium perborate tetrahydrate incorporated with the detergent may be one or two percent or even up to five percent based on the entire composition. If compositions with greater bleaching power are desired, then the perborate concentration may be increased to 10% and 20% levels without departing from the spirit of the invention.

The invention is applicable in the production of granular detergent products from soap, from synthetics of the anionic and nonionic classes, and from mixtures thereof. In other words, all non-cationic surface active agents which possess pronounced detergent properties may be combined with sodium perborate tetrahydrate in accordance with our discovery to produce the improved cleansing and bleaching agents herein disclosed. More particularly, the detergent substances include:

(1) Easter soluble soaps, such as the sodium salt of a mixture atty an s which contains about 85% of the mixed fatty acids derived from tallow and about 15% of the mixed fatty acids derived from coconut oil.

(2) WW such as the sodium salts of the sulfuric aci ester 0 mixed fatty alcohols derived from coconut oil or tallow.

(3) Water soluble salts of the sulfuric acid ester of fatty acid monoglycerides, such as the sodium salt of the coconut oil fatty acid monoester of 1,2-dihydroxy-propane-B-sulfuric acid.

(4) Water soluble salts of alkyl benzene sulfonic acids such as the sodium salt of the sulfonic acid derived from the condensation product of benzene and a propylene tetramer.

(5) Water soluble salts of fatty acid monoesters of low hydrate equal to 5% of the total composition. This mix- 5 ture was then passed continuously through a rotgtm' g drum wherein liquid organic uilder substances were in:

molecular weight hydroxy and polyhydroxy alkyl sulfonic acids, such as the alkali metal salts of coconut oil fatty acid monoester of 1,2-dihydroxy-propane-3-sulfonic acid.

(6) -Water soluble salts of alkyiglyceryl ether sulfonates, such as the sodium salt of coconut oil alccfiiol nTcinoether of l,2-dihydroxy-propane-B-sulfonic acid.

(7) Water soluble salts of alkyl ethers of polyethylene oxide sulfates, such as the sodium salt of the sulfuric acid ester of the coconut oil alcohol ether of triethylene glycol.

(8) Eonionic detergents of the ethylene-oxide alkylphenol condensation type, such as octyl phenol polyether alcohol containing about 11 ethylene-oxide groups.

Such detergents as above designated can be used alone or in combination with organic and inorganic builder substances when producing the cleansing and bleaching agents of the present invention. For example, the invention is applicable in the manufacture of heavy-duty synthetimdetergentswhichnarelell lgngwn in the commercial art and which contain massive amounts of tri polyphosphate. However, the presence of tripolyphosphate or of other builder substances, such as silicates, carbonates, amides, and the like, is not essential and detergent compositions containing no such builder substances, or only small amounts thereof, may be combined with perborate in accordance with the practice herein described.

The invention will be illustrated by the following examples, but it is understood that the scope of the invention is to be determined by the limitations in the claims rather than by the specific conditions of disclosure in the examples.

Example 1.- An aqueous slum, comprising a mixture of tetra ro lene benzene sulfonate and alkyl sulfate derived from a mixture of higher alcohols having 10 to 18 carbon atoms together with tripolyphosphate in amount equal to about three times the weight of organic sulfate and sulfonate, was sprayed into a conventional drying tower to produce granules having about 10% moisture content. The granules, at a temperature of 190' F. to 200 F., were removed continuously from the trodu o .n -r mm the ranules. The product issuing from the drum was immediately picked up by means of an air lift and deposited in suitable bins preparatory to packaging. In passage through the air lift the granules were cooled to a temperature below F.

Microscopic examination of the product showed that the sodium perborate tetrahydrate crystals were not visible as they are in a comparable mechanical mix. Rather, the perborate was absorbed by the granules to produce a product which, after severe jolting and handling, was uniform in perborate content as determined by analytical means.

The product resulting from the above process possessed adequate cleansing power and was comparable in bleaching power to a carefully prepared and unsegregated mechanical mixture of the same detergent with 5% of perborate.

The process can be repeated with other synthetic detergent, or soap, with similar improved results in the stability of the product against gravitational separation of perborate, but without appreciable decomposition of the perborate.

Example 2.A detergent composition was in Example 1 except that 10% sodium perborale tetrahydrate was employed and except iliat go l1gu1H organic builder substances were added during passage of the granular detergent mixture through the rotating drum. Samples of the resulting product in cartons were taken from the packing line. Half of the samples were jolted 250 times with the carton upright, 100 times with the carton on its side, and then 250 times again with the carton upright to simulate severe agitation that might be experienced during handling. The remaining samples were not subjected to the jolting procedure. Available 0, analyses were made on portions of product taken from the top, middle, and bottom of cartons in each of the two groups of samples. The data showed that there was no significant segregation of perborate.

The products were also examined under the microscope along with a sample prepared by mechanically mixing 10% perborate with cold detergent granules. 1n the mechanical mix, the crystals of perborate were readily observed in admixture with the detergent granules, but in the products of this example, perborate crystals could not be observed. Available oxygen analyses indicated that all perborate was present, but the original crystals were not visible, showing absorption of the perborate by the detergent granules.

Washing tests with the product of the example as compared with the mechanical mixture showed that the products were substantially the same in both washing and bleaching performance.

Having thus described our invention we claim:

1. A process of producing a non-segregating granular detergent product having bleaching power during use in aqueous solutions in washing operations, comprising admixing sodium perborate tetrahydrate crystals with previously spray dried granular non-cationic synthetic organic detergent at a temperature within the range of about F. to about 230 F., said temperature being sufficient to melt said perborate tetrahydrate to form a solution of the perborate in its water of crystallization, which solution, without substantial decomposition of perborate, is absorbed by outer pores and surfaces of detergent granules, then, promptly and within five minutes cooling the resulting product before substantial decomposition of perborate occurs.

2. In the process of producing a non-segregating granular detergent product having bleaching power during use in aqueous solutions in washing operations, the steps of spraying an aqueous non-cationic synthetic organic detergent slurry into a heated atmosphere to reduce moisture content and produce a porous granular spray dried product having a temperature within the range of about 180 F. to about 220 F., continuously removing the porous granular product from the drying zone, then, before the temperature drops to less than 145 F. continuously adding to and incorporating with the heated porous granular detergent from about 5% to about 20% of sodium perborate tetrahydrate crystals of average size not substantially greater than the average size of the granular detergent, permitting the said tetrahydrate to melt and form a solution, without substantial decomposition of perborate, which is absorbed by outer pores and surfaces of detergent granules, then, within five minutes and before substantial decomposition of the tetrahydrate, conveying the product to the successive stage of operation with relatively cool air, and cooling the product to effect solidification of absorbed perborate.

Menace: Cited in the file of this patent UNITED STATES PATENTS 2,308,992 Mertens Jan. 19, 1943 2,491,789 Young Dec. 20, 1949 2,524,394 Madorsky Oct. 13, 1950 2,623,856 Sanders Dec. 30, 1952 2,657,797 Ledgett et al. Nov. 3, 1953 2,706,178 Young Apr. 12, 1955 FOREIGN PATENTS 8,483 Great Britain of 1915 428,878 Germany May 12, 1926 

1. A PROCESS OF PRODUCING A NON-SEGREGATING GRANULAR DETERGENT PRODUCT HAVING BLEACHING POWER DURING USE IN AQUEOUS SOLUTIONS IN WASHING OPERATIONS, COMRISING ADMIXING SODIUM PERBORATE TETRAHYDRATE CRYSTALS WITH PREVIOUSLY SPRAY DRIED GRANULAR NON-CATIONIC SYNTHETIC ORGANIC DETERGENT AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 150*F. TO ABOUT 230*F., SAID TEMPERATURE BEING SUFFICIENT TO MELT SAID PREBORATE TETRAHYDRATE TO FORM A SOLUTION OF THE PERBORATE IN ITS WATER OF CRYSTALLIZATION, WHICH SOLUTION, WITHOUT SUBSTANTIAL DECOMPOSITION OF PERBORATE, IS ABSORBED BY OUTER PORES AND SURFACES OF DETERGENT GRANULES, THEN, PROMPTLY AND WITHIN FIVE MINUTES COOLING THE RESULTING PRODUCT BEFORE SUBSTANTIAL DECOMPOSITION OF PERBORATE OCCURS. 